Method of making water impervious materials

ABSTRACT

A water impervious laminated material is described. A preferred embodiment comprises a three-layer plastic film sandwiched between and fuse bonded to two layers of conjugate fibers having a low melting sheath and a high melting core. The inner layer of the plastic film is relatively high melting while the two outer plies of the film are low melting. The sheaths of the conjugate fibers have been fuse bonded to the plastic film at a temperature below the melt temperature of the cores of the conjugate fibers so that the cores retain their initial fiber-like integrity.

This is a division of application Ser. No. 689,123, filed Jan. 7, 1985now U.S. Pat. No. 4,595,629 which, in turn, is a division of applicationSer. No. 588,037, filed Mar. 9,1984 now U.S. Pat. No. 4,522,203.

This invention relates to water impervious laminated materials and moreparticularly to absorbent disposable drapes which are impermeable to thepassage of microorganisms and fluids.

BACKGROUND OF THE INVENTION

The purpose of the surgical drape is to place a bacteria barrier betweenthe aseptic operative field and areas which are incapable of surgicalcleansing. The drape also provides the physician while working on thepatient, a sterile area on which to lay surgical instruments and thelike. The drape should be sufficiently flexible or drapable so that itmay somewhat conform to the contour of the body which it is covering,and so that it may hang down over the edges of the operating tablewithout interfering with the physician's work. The drape should beabsorbent so that it may collect exudate from the operative site andshould also provide enough friction so that the drape does not slide offthe patient during the operation.

Certain known disposable drapes consist of nonwoven mats of heat fusiblefibers fused to one or both sides of thermoplastic sheets. However, inproducing this type of fabric, the heat fusible fibers are fused so thatthe integrity of the fibers is destroyed. The present invention providesa multiple layer plastic film fuse bonded on at least one side to alayer of conjugate fibers having a low melting sheath and a high meltingcore. The sheaths of the conjugate fibers are fuse bonded to the plasticfilm at a temperature below the melt temperature of the cores of theconjugate fibers so that the cores retain their initial fiber-likeintegrity. A preferred embodiment of the present invention comprises athree-layer plastic film sandwiched between and fuse bonded to twolayers of conjugate fibers. The inner layer of the plastic film isrelatively high melting while the two outer layers of the film are lowmelting, the melt temperature of the outer layers of the film beingclose to the melt temperature of the fiber sheaths, so that excellentfusion takes place when these fiber sheaths and the outer layers of thefilm are bonded together or emboss bonded. In addition, the inner coreof the three-layer plastic film is not fused during the bondingprocedure and this prevents any perforations being formed in the plasticfilm during emboss bonding.

THE PRIOR ART

Ross in U.S. Pat. No. 3,695,967 describes a laminated material havingfibrous surfaces made by laminating a nonwoven fibrouslayer/thermoplastic film/nonwoven fibrous layer assembly. Lamination ofthe assembly is accomplished by pressing it with at least one surfacewhich has a multiplicity of closely spaced raised areas while heatingthe assembly so that at least a portion of the thermoplastic film israised to a temperature above its softening point. There is nodisclosure in Ross concerning the use of conjugate fibers, and, in anyevent, the laminated material produced by Ross is perforated and thuswould not be suitable for use as a drape which necessarily must be madeimpermeable to the passage of microorganisms and fluids.

A number of patents disclose the general concept of bonding a nonwovenfibrous bat to a water impervious plastic film, but in no case is thereany disclosure concerning the desirability of utilizing conjugate fibersin the nonwoven bat, and thus when fuse bonding takes place between thenonwoven non-conjugate fibers and the plastic sheet, said fibers willtend to melt in the areas wherein fusion takes place and completely losetheir fiber-like integrity. This has the effect of reducing the loft orlow bulk density characteristics of the nonwoven bat so that theabsorption capacity and strength of the bat is also reduced. Examples ofpatents disclosing the bonding of bats of monofilament fibers to plasticsheets are as follows: Stoller, U.S. Pat. No. 3,988,519; Portolani, U.S.Pat. No. 3,551,284 and Prentice, U.S. Pat. No. 3,676,242.

The Gore et al. U.S. Pat. No. 4,194,041 describes a waterproof laminatecomprising an outer layer of a hydrophobic material and an inner layerwhich permits the transfer of moisture vapor. Textile layers can beadded for strength and aesthetic characteristics. The textile layers areon the outside of the laminate of the textile layers and the hydrophobicand moisture-vapor permeable layers. No conjugate fibers are disclosed.

The Falcone U.S. Pat. No. 3,513,057 describes a process for bondingtextile fibers to elastomeric ethylene/higher alpha-olefin copolymers.In this case, too, no conjugate fibers are disclosed.

The Hansen U.S. Pat. No. 3,809,077 discloses a surgical drapeconstructed of two layers of thin absorbent compacted webs of randomlyinterlaced staple textile fibers having disposed therebetween a thindrapable impervious sheet of a thermoplastic film which is adherentlybonded to the absorbent sheets across the contacting surfaces thereof bymeans of a soft latex adhesive. The fuse bonding of conjugate fibers isnot disclosed.

The present invention provides a soft drapable composite which isimpervious to water. The use of conjugate fibers composed of higher andlower melting components, preserves the integrity of the higher meltingcomponent, in view of the fact that the fusion process is carried outbelow the melting temperature of the higher melting component. Thepreservation of the integrity of the fibers, maintains the high loft orlow bulk density characteristics of the nonwoven layers in order toachieve good absorption capacity and strength. Furthermore, inaccordance with a preferred embodiment of the present invention, themelt temperature of the outer layers of the plastic film is chosen so asto substantially match the melt temperature of the lower meltingcomponent of the conjugate fiber. In this manner a far stronger and moreintimate bond is formed, especially in the instance wherein the samematerial is used for the outer layer of the plastic sheet as well as thelower melting component of the conjugate fiber.

In addition, the preferred embodiment of the present invention utilizesa plastic sheet comprising a three-layer coextruded film in which thecentral layer possesses a higher melt temperature than the two outerlayers. It is very unlikely that the inner layer of the three-layercomposite plastic film, would be punctured during emboss bonding,especially in view of the fact that said inner layer is chosen topossess a melt temperature above that at which bonding between theplastic sheet and the layers of conjugate fibers, takes place. Thisfeature is highly important in the case of a barrier drape in whichbacterial transfer must be prevented.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a waterimpervious laminated material comprising at least one layer of conjugatefibers, said layer of conjugate fibers having a first face and anopposite face, the conjugate fibers being composed of a lower meltingcomponent and a higher melting component wherein a substantialproportion of the surfaces of said fibers comprises said lower meltingcomponent, said lower melting component of said conjugate fibers whichlie on said first face being fuse bonded to a first layer of a plasticlaminated film which comprises said first layer and at least oneadditional layer, said first layer of said film being thermoplastic andpossessing a lower melt temperature than said additional layer of saidfilm, said lower melting component of said fibers having been fusebonded at a temperature below the melt temperature of said highermelting component of said fibers so that the latter component retainsits initial fiber-like integrity. Preferably, the melt temperature ofthe lower melting component of the conjugate fibers is not more than 35°C. higher or lower than the melt temperature of the first layer of thethermoplastic film.

In accordance with a preferred embodiment of the present invention,there is provided a water impervious laminated material comprising aninner plastic film sandwiched between two layers of conjugate fibers,each of said layers of conjugate fibers having a first face and anopposite face, said conjugate fibers being composed of a lower meltingcomponent and a higher melting component, wherein a substantialproportion of the surfaces of said fibers comprises said lower meltingcomponent, said plastic film comprising a three-layer structure havingan inner layer sandwiched between and bonded to two outer layers, saidinner layer of said film structure having a melt temperature higher thanthe melt temperatures of each of said outer layers of said filmstructure, said lower melting components of both layers of saidconjugate fibers which lie on said first faces having been fuse bondedto the adjacent outer layers of said film structure at a temperaturebelow the melt temperature of said higher melting component of saidfibers so that the latter component retains its initial fiber-likeintegrity.

In accordance with a further embodiment of the present invention, atleast one layer of conjugate fibers is blended with non-conjugatefusible fibers, with the proviso that the first face of said layer ofconjugate fibers contains a plurality of conjugate fibers in the blend.The specific nature and melt temperatures of the non-conjugate portionsof the blend are not critical since the conjugate-rich material in thefirst face of the layer which is fused to the plastic film ensures thegood bonding features provided by the present invention.

The outer layers of the film of the present invention (which constitutethe lower melting layers thereof) may consist of any suitable relativelylow melting thermoplastic polymer such as ethylene/propylene copolymer,polyester copolymer, low density polyethylene, ethylene/vinyl acetatecopolymer, polyethylene, chloronated polyethylene, or polyvinylchloride.A preferred higher melting inner layer of the plastic film comprisesisotactic polypropylene. However, a number of other higher meltingthermoplastic materials such as polyester or polyamide may also be used.

Although continuous filaments of conjugate fibers may be employed inaccordance with the present invention, nevertheless, the preferredconjugate fibers are textile length, that is they are fibers havinglengths of from 1/4 inch and preferably from 1/2 inch up to about 3inches or more in length. Such conjugate fibers can be bi-componentfibers such as the sheath/core or side-by-side bi-component fiberswherein there is a lower melting component and a higher meltingcomponent, with a significant proportion and preferably a majorproportion of the surface of the fiber being the lower meltingcomponent. Preferably the lower melting component is a polyolefin, andmost preferably polyethylene. In many cases the sheath/core bi-componentfibers are preferred because they exhibit a better bonding efficiencythan the side-by-side bi-component fibers, and because in some cases theside-by-side bi-component fibers may exhibit an excessive tendency tocurl, crimp, or shrink during the heat bonding step. Both concentric andeccentric sheath/core bi-component fibers can be used.

The nonwoven conjugate fiber layers of the present invention can havebasis weights from about 0.25 to about 3.0 ounces per square yard. Thebulk density of said layers of conjugate fibers will be below about 0.1grams per cubic centimeter, e.g., from about 0.03 to about 0.08 gramsper cubic centimeter, and preferably from 0.04 to about 0.06 grams percubic centimeter. The conjugate fiber nonwoven layers used in thepresent invention have a good absorbent capacity, and the excellentresistance of the nonwoven layers to wet collapse contributes to thisgood absorbent capacity.

In the thermal bonding step the lower melting component of the conjugatefiber is at least partially fused so that where the fused surfacetouches another conjugate fiber, welding or fusing together of the twofibers will occur. It is important in order to achieve the objects ofthis invention that the conjugate fibers remain fibers, i.e., that thehigher melting component of the conjugate fiber not melt or shrinksignificantly and thereby become beads or the like.

In accordance with a preferred embodiment of the present invention, theinner layer of the film structure comprises isotactic polypropylene andthe two outer layers comprise ethylene/vinyl acetate copolymer. Thepreferred conjugate fiber comprises a polyethylene/polyester sheath/corebi-component fiber. A further desirable embodiment of the film used inthe present invention is one in which the inner layer comprisesisotactic polypropylene and the two outer layers comprise polyethylene.Yet a further desirable embodiment of the film used in the presentinvention is one in which the inner layer comprises isotacticpolypropylene, one of the outer layers comprises polyethylene and theother of the outer layers comprises ethylene/vinyl acetate copolymer.

The preferred three-layer film used in the present invention ispreferably initially prepared by coextrusion in accordance with methodswell known in the art. However, said three-layer film structure may alsobe prepared by laminating separate components together and thereaftersaid components may be heat bonded together or bonded by means ofsuitabIe adhesives.

The present invention also includes a process for preparing a waterimpervious laminated material comprising at least one layer of conjugatefibers, said layer of conjugate fibers having a first face and anopposite face, said conjugate fibers being composed of a lower meltingcomponent and a higher melting component, wherein a substantialproportion of the surfaces of said fibers comprises said lower meltingcomponent, said lower melting component of said conjugate fibers whichlie on said first face being fuse bonded to a first layer of a plasticlaminated film which comprises said first layer and at least oneadditional layer, said first layer of said film being thermoplastic andpossessing a lower melt temperature than said additional layer of saidfilm, said lower melting component of said fibers having been fusebonded at a temperature below the melt temperature of said highermelting component of said fibers so that the latter component retainsits initial fiber-like integrity;

said process comprising forming an assembly of said laminated film andat least one layer of said conjugate fibers placed adjacent to saidfirst layer of said laminated film;

subjecting said assembly to a temperature sufficient to fuse said lowermelting component of said conjugated fibers which lie on said first faceas well as the first layer of the film in contact with said fiberswithout fusing the higher melting component of said conjugate fibers northe additional layer of the film, while maintaining said assembly underminimal pressure;

and cooling said assembly to resolidify said lower melting component ofthe fibers as well as its first layer of said film, whereby said fibersare firmly bonded to said film without impairing the integrity of saidhigher melting component of said fibers.

In accordance with a preferred embodiment of the invention there isprovided a process for preparing a water impervious laminated materialcomprising an inner plastic film sandwiched between two layers ofconjugate fibers, each of said layers of conjugate fibers having a firstface and an opposite face, said conjugate fibers being composed of alower melting component and a higher melting component, wherein asubstantial proportion of the surface of said fibers comprises saidlower melting component, said plastic film comprising a three-layerstructure having an inner layer sandwiched between and bonded to twoouter layers, said inner layer of said film structure having a melttemperature higher than the melt temperatures of each of said outerlayers of said film structure, said lower melting components of bothlayers of said conjugate fibers which lie on said first faces havingbeen fuse bonded to the adjacent outer layers of said film structure ata temperature below the melt temperature of said higher meltingcomponent of said fibers so that the latter component retains itsinitial fiber-like integrity;

said process comprising forming an assembly of said film sandwichedbetween two layers of said conjugate fibers, subjecting said assembly toa temperature sufficient to fuse said lower melting components of saidconjugate fibers which lie on said first faces in both of said layersthereof as well as both of said outer layers of said film without fusingthe higher melting components of said conjugate fibers nor the innerlayer of the film, while maintaining the assembly under minimalpressure, and cooling said assembly to resolidify said lower meltingcomponents of the fibers as well as the outer layers of the film,whereby said fibers are firmly bonded to said film without impairing theintegrity of said higher melting component of said fibers.

The above mentioned fusing step may be carried out by means of a heatedembossing calender or by passing the assembly through an oven while saidassembly is held between two porous belts under light pressure.Furthermore, the thermal bonding step may also be carried out by anyother suitable means for applying localized heat such as by sonic means,lasers, infrared heating or other types of radiant heating.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevation of an apparatus suitable forcarring out the process of the invention; and

FIG. 2 is a cross-section of the laminated material of the presentinvention.

Referring first to FIG. 1, one preferred arrangement of an apparatus forcarrying out the process of the invention is disclosed. The apparatusshown in FIG. 1 is suitable for making the laminated material of theinvention comprising a core of a three-layer film with facings ofheat-fusible conjugate fibers on both faces of said core. A web 10 ofheat-fusible conjugate fibers is laid down as from a card 12 on anendless belt 14. A laminated three-layer plastic film 20, fed fromroller 22, is then laid on top of web 10. The laminated three-layer film20 may be prepared by known coextrusion means. Film 20, after havingbeen laid upon web 10 forms a double layer web 28.

Web 28 is then passed under another station wherein a second web ofheat-fusible conjugate fibers 30 is laid on top as from a card 32.Although webs 10 and 30 are preferably prepared from cards,nevertheless, air-laid webs may also be used although the latterprocedure is not particularly suitable in the instance wherein the websare light weight. Although webs 10 and 30 are preferably fuse bonded ina subsequent step, said webs 10 and 30 may have been initially fusebonded, in a prior step, before they are laid on either side of thelaminated film 20.

After web 30 is laid on top of the double layer web 28, the resultingtriple layer web 34 is then passed through a fusion unit 36 to fuse thelower melting component of the conjugate fibers in webs 10 and 30 whilemaintaining the integrity of the higher melting component of thesefibers as fibers, and to fuse or soften the outer surfaces of thelaminate film 20 so as to securely bond webs 10 and 30 on either side oflaminated film 20. When the multiple layer web emerges from the fusionunit 36, it cools to thereby form the material 38 of the invention. Whenthe material 38 cools, the fused lower melting component of theconjugate fibers, solidifies, and bonds then form where their surfacestouch other fibers. The material 38 is then collected on a conventionalwind-up 40. Any suitable means of fusion bonding may be used in fusionunit 36 such as by means of a conventional heated embossing calender, orby passing the assembly through an oven while said assembly is heldbetween two porous belts under light pressure.

FIG. 2 shows a cross-sectional view of the laminated material of thepresent invention. Thus the laminated plastic film 20 comprising lowmelting outer layers 13 and 15 and higher melting inner layer 14 areshown sandwiched between layers 10 and 30 of conjugate fibers. Thetemperature of the fusion unit 36 is maintained below that of the melttemperature of the higher melting component of the conjugate fibers aswell as below the melt temperature of inner layer 14 of the laminatedfilm 20. In the instance wherein film 20 consists of a polypropylenecore 14 and low melting ethylene/vinyl acetate copolymer layers 13 and15, sandwiched between two layers of conjugate fibers 10 and 30comprising a polyethylene/polyethyleneterephthalate sheath/corebi-component fiber, the temperature maintained in the fusion unit(whether the composite is belt or embossed bonded) is preferably in therange of 135° C. to 145° C.

The exact temperatures employed in the fusion unit 36 will depend uponthe nature of the conjugate fiber used and the dwell time employed inthe fusion unit. For instance when the lower melting component of theconjugate fiber is polyethylene, the bonding temperature is usually fromabout 110° C. to about 150° C., and when the lower melting component ispolypropylene, the bonding temperature is usually from about 150° C. toabout 170° C. Dwell times in the fusion unit will usually vary fromabout 0.01 seconds to about 15 seconds. Specific conditions under whichthe thermal bonding is achieved are illustrated in the examples below.The temperatures referred to are the temperatures to which the fibersare heated in order to achieve bonding. In order to achieve high speedoperations, much higher temperatures with short exposure times can beused.

The examples below illustrate various aspects of the invention.

EXAMPLE 1

A laminated material is prepared by a procedure analogous to thatillustrated in FIG. 1 from an inner layer of a tri-component filmconsisting of one outer layer of ethylene/vinyl acetate copolymer (EVA),a polypropylene core, and the other outer layer being polyethylene. Thetri-component film is approximately 1 mil thick. The polyethylene has asoftening range of 110°-125° C. and a melting point of about 132° C. Thepolypropylene has a softening range of 145°-160° C. and a melting pointof 165° C. The ethylene/vinyl acetate copolymer has a softening range of90°-100° C. and a melting point of about 110° C.

A card web (which has already been through-air bonded) and weighing 0.5ounces per square yard, of high densitypolyethylene/polyethyleneterephthalate sheath/core bicomponent conjugatefiber was placed on each side of the above-mentioned tri-component film.The conjugate fiber had an concentric core and the fiber lengths wereabout 1.5 inches and the denier was 3. The high density polyethylenesheath had a softening range of 110°-125° C. and a melting point ofabout 132° C. The polyethyleneterephthalate core has a softening rangeof 240°-260° C. and a melting point of about 265° C. The polyethylenecomprised 50% of the conjugate fiber.

The film and the facings were laminated together using a hot press atabout 145° C.

In view of the fact that the two outer surfaces of the tri-componentfilm had different melting temperatures the polyethylene side was placedin contact with the hot plate in order to achieve complete lamination.This resulted in overbonding on the EVA side of the tri-component filmso that the resultant laminated material became somewhat stiff.

EXAMPLE 2

A laminated material was made by a procedure analogous to thatillustrated in FIG. 1 using a tri-component film consisting of a core ofpolypropylene sandwiched between two layers of low meltingethylene/vinyl acetate copolymer. The thickness of the film was 1 mil.The polypropylene core had a softening range of 145°-160° C. and amelting point of about 165° C. The ethylene/vinyl acetate copolymer hada softening range of 90°-100° C. and a melting point of about 110° C.

Webs of through-air bonded conjugate fibers (0.5 ounces per square yardbulk) prepared by card webbing were placed on either side of thetri-component film. The conjugate fibers consisted of high densitypolyethylene/polyethyleneterephthalate sheath/core bi-component fibers,the core being concentric. The high density polyethylene in theconjugate fibers had a softening range of 110°-125° C. and a meltingpoint of about 132° C. The polyethyleneterephthalate core of theconjugate fibers had a softening range of 240°-260° C. and a meltingpoint of about 265° C. The polyethylene comprised 50% of the conjugatefiber.

The conjugate fiber webs were laminated to the tri-component film usinga hot press at about 135° C. A minimal compression was applied in orderto maintain the bulk of the conjugate fiber facings. The resultingmaterial is a soft, drapable fabric composite which is impervious towater.

EXAMPLE 3

Example 2 is repeated with the following modifications:

Only a two-component film is used, the lower melting component, (namelythe ethylene/vinyl acetate copolymer) is placed facing upwardly, withthe next layer of polypropylene facing downwardly. Thereafter, only onelayer of the high density polyethylene/polyethyleneterephthalateconjugate fibers is placed on top of the film, with the lower layer ofconjugate fibers being omitted. Otherwise, the bonding procedure is thesame as that carried out in connection with Example 2. The resultantcomposite material is a soft drapable fabric.

Certain properties of the material obtained in accordance with Example 2are as follows:

Thickness of each conjugate fiber facing 20 mil.

Thickness of the tri-component film 1 mil.

Weight of composite material ounces/yard² 1.5 oz/yd².

The material produced in accordance with Example 2 is suitable for useas an operating room drape, a tray cover for surgical instruments,laporatomy packs, obstetric packs, backing layers for diapers orsanitary napkins and for any other applications wherein an absorbentimpermeable material would be desirable.

The material produced in accordance with Example 2 possesses improvedintegrity, durability, and strength as well as good absorptive capacitywith respect to the facing layers. Furthermore, in view of the fact thatthe high melting component of the conjugate fibers of the facing layersretain their fiber-like integrity, the bonding strength of the layers ofconjugate fibers to the plastic film is much greater than would be thecase if non-conjugate filaments only were to be used for the nonwovenfacing layers which are bonded to the water impermeable film. Anotheradvantage of the use of the conjugate fibers of the present invention isas follows: Pinholing of the film due to the high pressure andtemperature used is negated.

I claim:
 1. A process for preparing a water impervious laminatedmaterial comprising at least one layer of conjugate fibers, said layerof conjugate fibers having a first face and an opposite face, saidconjugate fibers being composed of a lower melting component and ahigher melting component, wherein a substantial proportion of thesurfaces of said conjugate fibers comprises said lower meltingcomponent, said lower melting component of said conjugate fibers whichlie on said first face being fuse bonded to a first layer of plasticlaminated film which comprises said first layer and an additional layer,said first layer of said film being thermoplastic and possessing a lowermelt temperature than said additional layer of said film, said lowermelting component of said fibers having been fuse bonded at atemperature below the melt temperature of said higher melting componentof said fibers so that the latter component retains its initialfiber-like integrity;said process comprising forming an assembly of saidlaminated film and at least one layer of said conjugate fibers placedadjacent to said first layer of said plastic film; subjecting saidassembly to a temperature sufficient to fuse said lower meltingcomponent of said conjugate fibers which lie on said first face as wellas the first layer of the film in contact with said fibers withoutfusing the higher melting component of said conjugate fibers nor theadditional layer of film, while maintaining said assembly under minimalpressure; and cooling said assembly to resolidify said lower meltingcomponent of the fibers as well as said first layer of said film,whereby said fibers are firmly bonded to said film without impairing theintegrity of said higher melting component of said fibers.
 2. A processfor preparing a water impervious laminated material comprising an innerplastic film sandwiched between two layers of conjugate fibers, each ofsaid layers of conjugate fibers having a first face and an oppositeface, said conjugate fibers being composed of a lower melting componentand a higher melting component, wherein a substantial proportion of thesurfaces of said fibers comprises said lower melting component, saidplastic film comprising a three-layer structure having an inner layersandwiched between and bonded to two outer layers, said inner layer ofsaid film structure having a melt temperature higher than the melttemperatures of each of said outer layers of said film structure, saidlower melting components of both layers of said conjugate fibers whichlie on said first faces having been fuse bonded to the adjacent outerlayers of said film structure at a temperature below the melttemperature of said higher melting component of said conjugate fibers,so that the latter component retains its initial fiber-likeintegrity;said process comprising forming an assembly of said filmsandwiched between two layers of said conjugate fibers; subjecting saidassembly to a temperature sufficient to fuse said lower meltingcomponents of said conjugate fibers which lie on said first faces inboth of said layers thereof as well as both of said outer layers of saidfilm without fusing the higher melting components of said conjugatefibers nor the inner layer of the film, while maintaining the assemblyunder minimal pressure; and cooling said assembly to resolidify saidlower melting components of the fibers as well as said outer layers ofsaid film, whereby said fibers are firmly bonded to said film withoutimpairing the integrity of said higher melting component of said fibers.3. The process of claim 1, wherein said fusing is carried out by meansof a heated embossing calender, or by passing the assembly through anoven while said assembly is held between two porous belts under lightpressure.
 4. The process of claim 2, wherein said fusing is carried outby means of a heated embossing calender, or by passing the assemblythrough an oven while said assembly is held between two porous beltsunder light pressure.